JPH01208805A - Thin-film temperature sensor - Google Patents

Abstract

PURPOSE:To scale down an external shape, to reduce thermal response and to select TCR, a resistance value, etc., within wide ranges by forming a heating element thin-film onto an insulating base body and shaping a temperature element thin-film onto the heating element thin-film through an insulating thin-film. CONSTITUTION:A heating element thin-film 12 having 5000Angstrom thickness and made of tungsten is formed onto an insulating base body 11 having 0.3mm thickness and made of quartz, and a heating element having 20OMEGA is manufactured through etching, etc. An insulating thin-film 13 having 4000Angstrom thickness and made of silicon nitride and further a temperature element thin film 14 having 4000Angstrom thickness and made of nickel are shaped onto the thin-film 12, and a temperature element having 300OMEGA is prepared through etching, etc. A protective film 15 having 5000Angstrom thickness and consisting of silicon dioxide is formed onto the thin-film 14, thus manufacturing a thin-film temperature sensor. Accordingly, since small geometry is shaped and a distance between the heating element and the temperature element is shortened, thermal response is reduced and both the heating element and the temperature element can be prepared separately, thus widely selecting resistance temperature characteristics (TCR) peculiar to a metal and a resistance value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thin film temperature sensor that has a correlation between temperature change and resistance value change.

Conventional technology There are two types of metal temperature sensors that use metal's inherent resistance-temperature characteristics (TOR) to convert resistance variables into temperature variables and detect temperature: those that use metal wires and those that use thin films. There are two types. Among these, those using metal wires are used as temperature sensors, such as those in which fine metal wires are stretched as they are, or those in which the metal wires are fixed by winding them in a spiral shape on an insulating substrate.

Problems to be Solved by the Invention In the above-mentioned temperature sensors that use metal wires, there is a limit to how thin the wires can be. It is necessary to increase the size sufficiently, which has the disadvantage that the two dimensions of the shape become large. And the shape.

As the size increases, the thermal responsiveness increases, which sometimes causes trouble as a temperature sensor.

On the other hand, if the first dimension of the shape is made smaller, the thermal response improves, but the metal wire becomes shorter, so the resistance value obtained becomes lower.
The amount of change in resistance value with respect to temperature change was small, and the signal amount was insufficient for use as a temperature sensor.

Also, when comparing the same resistance value, those made using thin films are compared to those made using metal wires, but because they can be made in a smaller shape with one dimension, the thermal response is smaller. It also has many advantages, such as the fact that it is easy to create a relatively high resistance value of up to several Ω. However, as a thermosensor, the resistance value has a large variation, that is, in the case of -TCR, a higher resistance value is advantageous, but from its role as a heat generating element, it has a negative effect on the applied voltage, applied power durability, etc. There is a limit to increasing the resistance value due to considerations, etc.
Conflicts sometimes arise when the same body serves as both a thermosensor and a heat generating body. As a way to improve this, Figure 2a,
As shown in b, a thin film temperature sensor has been proposed in which a heating element 22 and a temperature sensing element 23 are formed using thin films of the same material at a certain distance on an insulating substrate 21, and then a protective film 24 is provided. However, since thin films of the same material are used, the resistance value.

Limitations arose in TCH. Further, the distance between the heating element 22 and the temperature sensing element 23 is several tens to several hundreds of microns due to restrictions on pattern formation, and there are restrictions on further improving thermal responsiveness.

An object of the present invention is to improve thermal responsiveness without being restricted by the materials of the heating element and the temperature sensing element.

Means for Solving the Problems In order to solve the above problems, the present invention provides a thin film having a structure in which a heating element thin film is formed on an insulating substrate, and a temperature sensitive element thin film is formed on top of the heating element thin film via an insulating thin film. This is a temperature sensor.

Function: Since this configuration utilizes a thin film, it can be made with a small shape and one dimension, and has low thermal responsiveness. Furthermore, since the distance between the heating element and the temperature sensing element is the thickness of the insulating thin film, the thermal response can be reduced. Furthermore, since the heating element and temperature sensing element can be created separately, τOR,
Resistance values etc. can be selected from a wide range.

Example An embodiment of the present invention will be described below with reference to FIG.

A quartz substrate with a thickness of 0.3 # is used as the insulating base 11, a heating element thin film 12 made of tungsten with a thickness of 5,000 angstroms is formed on this, and a quartz substrate with a thickness of 20 nm is formed by etching or the like.
Ω heating element. An insulating thin film 13 of silicon nitride having a thickness of 4,000 angstroms is formed on this upper layer. On top of this, a nickel temperature sensitive thin film 14 with a thickness of 4,000 angstroms is formed and etched etc.
temperature sensing body.

A protective film 16 made of silicon dioxide having a thickness of 5,000 angstroms is formed on this upper layer to form a thin film temperature sensor in which a heating element and a temperature sensing element are provided in layers.

As described in detail, the present invention has a thin film structure, so one dimension of the shape is small, and the heating element.

Since the distance between the temperature sensitive body is small, the thermal response is as small as 0.26 seconds. Furthermore, since the heating element and the temperature sensing element can be manufactured separately, different resistance values can be easily created, such as 20Ω for the heating element and 300Ω for the temperature sensing element.

This results in a heating element that is constrained by the supply voltage;
Since the resistance value of the temperature sensor, which is preferably higher in order to increase the amount of change, can be created appropriately, it is possible to design a temperature sensor that is suitable for the usage conditions. The thermal response of the conventional example was 0.66 seconds.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a thin film temperature sensor according to an embodiment of the present invention, and FIGS. 2a and 2b are a plan view and a sectional view of a conventional thin film temperature sensor. 11...Insulating base, 12...Heating element thin film, 13...Insulating thin film, 14...
Temperature sensitive thin film, 15...Protective film.

Claims (1)

[Claims] A thin film temperature sensor in which a heating element thin film is formed on an insulating substrate, and a temperature sensing element thin film is formed on top of the heating element thin film with an insulating thin film interposed therebetween.